OPC Studio User's Guide and Reference
WaitForMultipleItemValues(IEasyDAClient,IReadOnlyList<ValueTuple<DAItemGroupArguments,DAQuality>>) Method



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess.Extensions Namespace > IEasyDAClientExtension2 Class > WaitForMultipleItemValues Method : WaitForMultipleItemValues(IEasyDAClient,IReadOnlyList<ValueTuple<DAItemGroupArguments,DAQuality>>) Method
The client object that will perform the operation.

This is typically the OpcLabs.EasyOpc.DataAccess.EasyDAClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

List of tuples, where each tuple consists of OPC-DA item group arguments, and a minimum quality determining when the wait is complete.

The value of this parameter cannot be null (Nothing in Visual Basic).

Waits until the OPC-DA items reach the given minimum quality. Specify arguments objects, and minimum qualities.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function WaitForMultipleItemValues( _
   ByVal client As IEasyDAClient, _
   ByVal argumentsAndMinimumQualityList As IReadOnlyList(Of ValueTuple(Of DAItemGroupArguments,DAQuality)) _
) As ValueResult()
'Usage
 
Dim client As IEasyDAClient
Dim argumentsAndMinimumQualityList As IReadOnlyList(Of ValueTuple(Of DAItemGroupArguments,DAQuality))
Dim value() As ValueResult
 
value = IEasyDAClientExtension2.WaitForMultipleItemValues(client, argumentsAndMinimumQualityList)

Parameters

client
The client object that will perform the operation.

This is typically the OpcLabs.EasyOpc.DataAccess.EasyDAClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

argumentsAndMinimumQualityList
List of tuples, where each tuple consists of OPC-DA item group arguments, and a minimum quality determining when the wait is complete.

The value of this parameter cannot be null (Nothing in Visual Basic).

Return Value

The function returns an array of OpcLabs.BaseLib.OperationModel.ValueResult objects. The indices of elements in the output array are the same as those in the input list, argumentsAndMinimumQualityList.

This method never returns null (Nothing in Visual Basic).

The individual elements of the returned value are never null (Nothing in Visual Basic).

Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Remarks

Subscribes to the specified OPC-DA items, and monitors their data until they have at least the quality specified for each item, an error occurs, or the alloted time elapses.

The server(s) can be local or can be remotely accessed via DCOM.

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also